1. Technical Field
The present invention relates to a piezoelectric drive device and various apparatuses such as a robot including a piezoelectric drive device.
2. Related Art
A piezoelectric actuator (piezoelectric drive device) which drives a driven body by vibrating a piezoelectric substance is used in various fields, since a magnet or a coil is not required (for example, JP-A-2004-320979). According to a basic configuration of the piezoelectric drive device, four piezoelectric elements are configured to be arranged in two rows and two columns on two surfaces of a reinforcing plate. Eight piezoelectric elements in total are disposed on both sides of the reinforcing plate. Each of the piezoelectric elements is a unit which interposes each piezoelectric substance between two electrodes. The reinforcing plate is used as one electrode of the piezoelectric element. One end of the reinforcing plate has a protrusion portion disposed in order to rotate a rotor by coming into contact with the rotor serving as a driven body. If an AC voltage is applied to the two piezoelectric elements arranged at opposite angles among the four piezoelectric elements, the two piezoelectric elements perform expansion and contraction movement. In response to the movement, the protrusion portion of the reinforcing plate performs reciprocating movement or elliptical movement. Then, in response to the reciprocating movement or the elliptical movement of the protrusion portion of the reinforcing plate, the rotor serving as the driven body is rotated in a predetermined rotation direction. The rotor can be rotated in the opposite direction by switching from the two piezoelectric elements to which the AC voltage is applied to the other two piezoelectric elements.
JP-A-2008-227123 is an example of the related art.
Incidentally, as a method of increasing force by which the piezoelectric drive device drives the driven body (hereinafter, referred to as a “drive force”), a method of simply using the above-described multiple piezoelectric drive devices in the related art is conceivable. However, in this case, if the multiple piezoelectric drive devices which are used are treated as one piezoelectric drive device as a whole, a problem arises in that the whole size of the piezoelectric drive device increases in proportion to the number of the piezoelectric drive devices which are used. Consequently, for example, since an arrangement space of a drive device is restricted as in a drive device for driving joints of a robot, there is a possibility that the piezoelectric drive device may be less likely to be employed as the drive device whose small size and high output power are desirable. Therefore, a suitable configuration of a miniaturized and lightweight piezoelectric drive device having high output power has not been sufficiently studied.